Garmin Fenix 8 Review, But Only The Internals (A.K.A. Teardown)

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When the weather is cold, it’s time for leaving running, hiking, cycling out and doing some indoor activities. One of the most exciting indoor activities is definitely teardowning. Especially if we have something new to tear down to it’s pants. And last year Garmin released a new toy or tool named Garmin Fenix 8. As an MIP display lover, I have a model with an MIP display. (Sorry AMOLED guys.) It’s Garmin Fenix 8 Solar 51 mm. In the past Garmin named 51 mm models ending with X suffix. However, this year we don’t have a Garmin Fenix 8X Solar but have a Garmin fēnix® 8 – 51 mm, Solar. I don’t know why. Why, why, why? Anyway, let’s go on with the teardown process. Btw, this watch will continue it’s daily duty after the operation, so I don’t disassemble it completely.

In one side of the body there is a colourful metal part with two holes on it, it is named sensor guard. So I firstly unscrew the torx screws on it and remove it. As it’s easy to disassemble if you want to paint it to a different colour, it’s apparently easy to do without painting the whole watch.

Here in the picture, the first and last holes are screw holes. The cavity in the middle is to allow air and water go out easily. Larger hole in the middle seems to be the barometer sensor to measure the air pressure, underwater depth etc. And the other one is a MEMS microphone I think. I don’t know exactly.

Now, on both faces of the watch there are four screws to go inside. I mostly prefer the front side because the battery and some other things may be glued to backside and I may have difficulty with it or break something. Usually, it’s very easy entering inside simply unscrewing the screws and slowly removing the bezel as it has connectors going to the motherboard.

Behind the bezel we have a newer and colourful gasket. It’s a blue one with green part on top. I don’t know why they preferred a colourful bezel but it definitely seems good. 🙂 In the past it was red, later became blue and now it’s transparent blue and green. Except that we have two connectors, larger one is for the display and the other is for the touchscreen and solar power thing. The display module is probably the same one being used since Fenix 6X model, 280 x 280 pixels reflective active matrix 1,39″ 64 colours display, Sharp LS014B7DD01. Apparently there are not important upgrades in MIP display technology as everywhere AMOLED is being preferred more. So we have our old friend inside our newest watch.

Now, put aside the bezel and look at the internal part. Here we see the green motherboard with metallic isolation fabric on it. Under the fabric we have lots of chips and components. We see two connectors for the display module. Downside we have the speaker module and its connector. Just near it, there is the battery connector. They’re glued so that they don’t get loose and dismantle themselves. You definitely don’t want to see your watch go kaput while vibrating tied on the handlebar of your mountain bike. Also we have six spring connectors around the motherboard, three on right side and three on the left. I haven’t traced lines on the motherboard but they’re probably there for transferring GNSS signals from location satellites and heart rate signals from your hand to the motherboard and appropriate circuitry. On the top there is a plastic part with a single screw on it. That little plastic is just there to prevent the connector under it from moving. That’s a connector for the upper module which contains the flaslight LEDs on it and another sensor similar to the one under the side metal which I believe to be a TDK MEMS microphone. In order to remove the motherboard we first need to unscrew that silver screw on top of the plastic and remove it. Then we can continue with black screws fixing the motherboard to the body. Also we need to carefully disconnect the connectors below the motherboard as they’re also glued and one is main battery line which we don’t want to harm in any way.

Back side of the motherboard doesn’t have a lot of interesting things. A few little ICs, and a lot of connectors. All connectors around the motherboard are for the buttons on the plastic case. There are four connectors aligned vertically. They connect to the USB cable pins on the backside of the watch, so that you can charge the watch and transfer music files or maps to your watch. Also there are a few larger golden pads on the motherboard. They’re just to interface with the spring connectors on the case. They’re probably to transfer heart rate signals from the arm to the motherboard. Or maybe something else.

Now let’s return to the case now as we’ll have more time to spend with the motherboard stuff.

Now you apparently see the large battery cell. It’s inside a nylon package and glued to the case. It’s a 3.91 volts 618mAh capacity li-ion battery with 2.42Wh rated energy. Some codes on it are: Garmin 361-00181-21 GB-S10-452534-010H and many more of it. I couldn’t understand the actual battery cell manufacturer from the texts on it. Fenix 7X battery was from Amperex, this may be too, or maybe not. There is another print writing NS25KS28BMWPS. Also the production date is written on it and it actually means the watch was sold only a month after the production of the battery. So all these candies are fresshh baby! 😀

Just behind the barometer holes there are two barometer like devices. Probably one is barometer and the other is depth gauge. I’m not exactly sure. Also back of one module is rectangular and there is one rectanguler module on top of the case near the LED module. Also there is a hole visible from outside the case there. It may be a similar gauge for back up, or better measurement. Or maybe it’s something else like a microphone etc. I really don’t know and I didn’t want to destroy it just to learn. 😀

Now, let’s move on to the motherboard, where I’m more interested. Of course now we’ll have a look at the front side. There is a large metallic fabric which acts as an EMF shield here. Simply pulling it from one side and removing it, lets us see everything inside. There is a kind of black tape underside the fabric.

When we look at the guts under the EMF shield, everything is tucked in to the place really well and there aren’t ample empty space around. However, there are some empty area around the EMF shield. Also we have some old friends inside. So let’s continue directly to chips.

“MRT595SFFOC is the brain of the device. It’s NXP’s low power crossover processor MX RT500. I.MX branding reminds me of heritage of Freescale Semiconductor which NXP acquired a few years ago. Previous Garmin watches used Freescale CPU’s too.”

If you came this site previously for similar reasons, you may remember those same words from an older teardown. 🙂 Yeah, this chip is our old friend. Garmin Fenix 8 shares the same main System On Chip with Garmin Fenix 7X. You can check that teardown here. But why did they use the same old chip? There are some rage in people hearing they use the old chip in the newest watch. Because they know chips in smartphones are upgraded every year. Other smart watch brands usually upgrade their chips every year.

But why Garmin doesn’t? Smartphones and those smartwatches run on large and heavy platforms which require really powerfull hardware. And there are competition over chips there. Not each new chip enables some function that previous chips can’t. But they increase frequency, core count, architecture, shrinks process size etc. There are a lot of different changes. Also the users are accustomed to get a new and better chip every year. Thus chip makers are hurrying to sell more chips to smartphone companies to earn more money. However, when you look at the chips used in sports watches, they’re chips preferred to be much low powered and much more simple to limit their power consumption. Thus ARM’s Cortex M architecture is being used since a long time. There are advancements in this architecture too, but they aren’t released and applied as fast as smartphone chips. Thus even the latest product may be based on a design a few years old. Even if you want the newest architecture, probably you won’t be able to find a chip to buy, as manufacturers follow those designs slower than smartphone chips manufacturers. It’s how this industry works. Apparently, there are a lot of reasons… Btw, this is not the same time Garmin used the chip of an older model. For example; Garmin Fenix 5X had the main chip of Garmin Epix.

When we look at the chip, it’s apparently powerful and rich enough to run Garmin’s OS and sports functions. Even, it’s some DSP capabilities etc. are maybe started to being used with this newer models as they have microphone and related functions. Now, I’ll get my old sentences for more information about the chip. 😀

It contains an ARM Cortex M33 CPU and also Cadence Xtensa Fusion F1 Audio Digital Signal Processor (DSP) CPU. ARM Cortex M33 is an update over older ARM Cortex M4 technology and Cadence Xtensa Fusion F1 DSP is capable for audio processing and other digital signal processing needs. Both processors have hardware floating point units. Both can run at up to 200 MHz frequencies. However, as usually purpose is power saving in these devices, they may be running at much lower frequencies. ıt has 2D GPU that can run at 200 MHz speed. Also this processor has 5 MB of on chip SRAM. Yeah, it has 5 MB RAM on it. Actually, this is not a single large 5 MB block, but there are 32 different blocks with size ranging from 32 KB to 256 KB. Each block can be powered independant of each other so that unused RAM may be powered off or put to low power mode to save power. Also subsystems such as graphics and DSP can access the memory via 64 bit interface while Cortex M33 core access at 32 bit interface. There are lots of other things about this chip, however, it’ll take too long to finish.

Shortly, NXP MRT595SFF0C is a dual core chip with one ARM Cortex M33 main chip and one proprietary DSP chip for mostly audio duties. It has internal 5 MB RAM to run apps and store map data. Also it has 2D GPU unit, which probably helps with more fluid graphics and maybe even map rendering. The note here is watches with mapping capabilities before Fenix 7 series had external RAM chips to store map data. For example Garmin Epix and Fenix 5X had 32 MB and Fenix 6X had 16 MB RAM chips. However, these chips consumed power and maybe added some latency to the job. Thus Fenix 7X doesn’t have an external memory chip and used the much faster but smaller SRAM on the chip to run maps. Fenix 8 follows the same fashion, too. Apparently, this works okay. However, map rendering is still slow on these watches. So in order to decrease storage access amount and increase map searching and rendering speed, they could have utilized some amount of external memory here. Also some watches from competition, other sports watch manufacturers I mean, seem to have such external RAM chips and run and render the maps more fluently. Of course they don’t utilize the maps as functional as Garmin does, and this may be the main reason why they render faster, I don’t know. But apparently we can’t help thinking it’d be faster or better with some more memory.

Now, let’s continue with the flash chip where the watch stores our data, maps and music etc. It’s a 32 GB subsize eMMC chip, Foresee FEMJNM032G-58C29. It’s a small and low power storage chip with 3D TLC nand flash and has read and write speeds of up to 90 MB/s. Endurance should be much more enough for us as our activities usually take less size than even a megabyte.

Ambiq Micro Apollo 3 – AMAP3 is another chip Garmin Fenix 8 and Fenix 7 series share. It is Apollo3 series chip from Ambiq Micro. I think it functions as a sensor hub. ,Apollo 3 has a Cortex M4F CPU core that can run up to 48 MHz and even 96 MHz in power sucking turbo mode. It has 384 KB of SRAM memory and 1 MB flash memory as a storage.

Another chip that didn’t get an upgrade over Fenix 7 is Silicon Labs RS9116-B00 dual mode WiFi and Bluetooth chip.

With this chip WiFi works at 2.4 GHz and supports a bandwidth up to 20 MHz with IEEE 802.11 b/g/n single stream. It has Bluetooth capabilities with dual mode Bluetooth 5 support. It supports Bluetooth 2.1 + EDR, Bluetooth Low Energy 4.0 / 4.1 / 4.2 / 5.0. I’m not sure where is the antenna four these are hidden though. The chip supports concurrent WiFi and Bluetooth but our devices usually don’t let this. Also this chip may be responsible for the ANT+ connection too.

Maxim MAX20360. Another old friend is the power management IC of the device from Maxim / Analog Devices. It does all the battery management and power management duties on the device, power substation inside the watch.

22T3XR is a chip by NXP which should be there to run the NFC functions of the watch.

Another chip we see is CS47L24 by Cirrus Logic. (Cirrus Logic bullettin, data sheet. It is an audio hub codec chip with dual core DSP. It’s probably being used for microphone processing but as I don’t know exactly how audio is handled in Garmin watches it may have different functions too. Basically main processor has DSP on it too, also other Cortex M4 chips on the board have audio capabilities. So only Garmin knows exactly which chip does what. Also I’m not willing to trace each path from microphones. 🙂

Basically it’s a capable audio processing chip.

Another chip is hard to read in the shade of metal. It says sth. like CYSC402 5FNI…

CY8C4025FNI 412 is Cypress/Infineon PSoC 4000S MCU. Shortly ARM Cortex M0+ programmable System on Chip solution of Cypress. 24 MHz 32 bit processor. It has capacitive sensing capability and it’s close to a connector coming from the display unit. So it’s apparently does the job of capacitive touch sensing. This guy calculates in which coordinate on the screen we put our finger or slide it from which site to which side etc…

Another interesting chip is another chip positioned near and below the metal shield frame.

SYN4778 is Garmin’s newest multi-band GNSS solution from Synaptics. It is a chip produced with 7 nm process and supports simultanous GPS, GLONASS, NAVIC, BeiDou, Galileo, SBAS, and QZSS in both the L1/B1/E1 and L5/E5/B2a frequency bands. When you put your watch in All Systems + Multi Band mode this guy handles that dual frequency and multi constellation location calculation job. Personally I was satisfied with GNSS performance of my Fenix 7X which was a single band unit. Now, I’m satisfied with results from this chip too. Also I always use it in auto mode as it saves more power by using features like dual frequency or multi constellation etc. just when needed. Even in this mode it gives me fairly good accuracy. So I don’t have a bad thing to say atm. However, I see there is a long GPS accuracy post on Garmin Enduro 3 section of Garmin Forums. So Enduro 3 may be using a different GNSS chip, antenna or maybe it’s just due to personal GPS taste. Also I couldn’t trace any specific antenna for GNSS reception, so it may be using the whole front bezel as an antenna.

These are the internals of Fenix 8. Yeah, there are many more components on the motherboard but I neither won’t look up every resistor or condensator on the board nor won’t reverse engineer this watch.

In short Fenix 8 adds a microphone and speaker to the Fenix 7 line with a newer software interface. We see some same chips with Fenix 7 like main CPU, BLE/WiFi chip etc. But also we have a newer GNSS chip made by completely different company. Storage chip is different, etc. There are changes but basically it is still a Fenix 7 hardware wise with a speaker and microphone. Yeah, you can dive with it now, thanks to Apple letting its watches to dive so bringing the competition to a better place. I think it’s enough for the teardown part. If you have any questions or things to add, don’t hesitate to write back. Also I may have some mistakes as I wrote this long long time after the teardown in a long long time. So I may have forgot sth. etc.

After the teardown let’s talk about the product. As I said I still think this is a Fenix 7 with microphone and speaker. Yeah, it has some newer functions and features but basically both do the same job, but in a bit different ways. Except the hardware, software got some updates and continues to be updated. As both devices almost share the same hardware, software could be transferred to Fenix 7 line, but we know Garmin won’t do this. Also I’m sure that I don’t want Garmin do that, anyway. Any new software means a lot of newer bugs to catch and kill. My Garmin Fenix 7X runs solid with its software and I believe it is better to have it with the software and functions I am already familiar with. In Fenix 8 they change some areas with updates and it seems to be more a hurdle than a feature. For example, last week I used the back track function. It’s a function I’ve been using since 10 years. However, this time it didn’t show me the remaining distance etc. I thought it was a bug, but after a bit of playing with menus I saw that those were moved to a different menu. Basically those watches do the same things, however, features are in different menus, settings are a bit different, interface is kinda different. Fenix 8 debuted with a lot of criticism due to its bugs. It may still have some little bugs here or there, however, usually works fine. Comparing with Fenix 7, Fenix 7 is still a solid buy with its price and functions. LEDs are brighter than F7 line. Personally speaker and microphone is good to have, but with some quirks. I get a call and I move my hand to answer it from my watch. However a sudden notification comes from Telegram app and phone answering section disappears from screen, then I have to take out my phone to answer it. Speaker sound is loud enough for basic alarm sounds etc. However, in a call it may not be enough in crowded or loud places. Phone assistant usage sometimes has issues, too. Not due to watch, but Google’s implementation and settings. When you break a setting or two, it’s hard to turn it back.I push the button, assistant animation starts while my phone is displaying its assistant screen and listening me from the phone, instead of the watch etc. I mean these are functions yet to be improved both on the watch and phone side etc.

Another point is price increase. Adding speaker, microphone, a better LED light and newer GNSS chip etc. costed us a lot of money. Additionally, we already pay these watches really big amounts of money. Competitors use many similar or same components with much cheaper prices. Garmin gave us Connect platform for free and it was one of the features that pulled me to the ecosystem. As we already paid a lot of money for our watches, we thought we already paid price of Connect, too. However, after the price increase in Fenix lineup we see Garmin tries to make the Connect platform a subscription based platform with Connect+. Yeah, all the old functions will continue to be on the platform for free. However, newer shenanigans like more more badges and some AI features now comes to the Connect+ subscribers. I hope Garmin doesn’t leave the Connect at this stage and only continue to update the Plus side of platform. Anyway, it turns to be a bit strange to pay a hell amount of money to a watch and continue to pay to use some features of it monthly. Strava moved to subscription side too but they don’t earn from their platform. So it may be accepted. But Garmin is already making a lot of money from here. Anyway, I’m not subscribing yet for 360 Turkish liras every month. We’ll see how it’ll affect other users and newer buyers.